The present disclosure relates to an energy absorbing structure for a vehicle with a chassis frame.
It has been known that a ladder-shaped chassis frame is provided with a vehicle called a small truck or a sport utility vehicle, for example as described in GB 2390581A or WO 2004/002808. The chassis frame is formed in a ladder shape by a pair of left and right main frames (also called side frames) extending in a vehicle longitudinal direction (i.e. vehicle front and rear direction) and multiple cross members connecting the left main frame to the right main frame.
The main frame is provided with an engine mount bracket for mounting an engine, a cab mount bracket for mounting a vehicular body component which may include a cabin which carries passengers and cargo.
Further, a pair of suspension towers may be attached to a front portion of the main frames to support a top portion of a strut of the front suspension, as described in GB 2390581A or WO 2004/002808.
A suspension tower, an engine mount bracket and at least one cross member would be attached to the front portion of the main frame. A front cross member is traditionally provided frontward of the suspension tower. The front cross member traditionally supports the front and inner end of an A-type lower arm of the front suspension. A rear cross member is traditionally provided rearward of the suspension tower. The rear cross member traditionally supports the rear and inner end of the A-type lower suspension arm. The suspension tower, the engine mount bracket and the front and rear cross members would be attached to the main frame within a relatively narrow range in the vehicle longitudinal direction. Given that suspension tower and the engine mount bracket, together with the main frames, may not easily deform in the vehicle longitudinal direction, the aforementioned components may not readily absorb energy during a vehicular front collision. On the other hand, lengthening the main frame may be restricted by a predetermined vehicle overall length. Therefore, the main frame may not adequately absorb energy and deform in the vehicle longitudinal direction.
Accordingly in the past, vehicle structures, such as but not limited to the suspension tower and the cross member, have overlapped one another in the vehicle longitudinal direction.
However, where multiple vehicle structures, such as but not limited to a suspension tower and cross member overlap each other in the vehicle longitudinal direction, the main frame is less likely to deform and therefore, less likely to absorb energy during a vehicular front collision. That is, this arrangement of the vehicle structures could result in an overall arrangement where the structural arrangement can not deform in a controlled manner in order to absorb energy from a collision. In contrast, where only one vehicle structure, such as a cross member alone, attaches to the main frame, this portion of the main frame may more readily compressively deform during a vehicular front collision.
Further, excessive impact force may disadvantageously be momentarily applied to the passenger in the cabin due to the joint between the main frame and the multiple vehicle structures. This is because the joint on the main frame which would be hard to compressively deform during vehicular front collision would cause the deceleration of the vehicle body rapidly increasing after the other part of the main frame (other than above joint between the main frame and the multiple vehicle structures) has already deformed.
The present disclosure is provided to address this issue. A purpose of the present disclosure is to absorb sufficient levels of energy during vehicular front collision (especially during a front full-lap collision) and to minimize energy absorption at the vehicle cabin area as much as possible.